GeneralDisorder Posted May 28, 2009 Share Posted May 28, 2009 (edited) What would be causing the lean conditions then? I read somewhere here that the fuel pumps were designed in mind with the alternator. Something about if the alternator is defunct, the pump wont. If you get in a wreck and the fuel line is cut, its designed to not pump fuel out if the alt isnt spinning. Only on 80/81 models. On 82 and newer the alternator is internally regulated and the fuel pump is controlled by a Fuel Pump Control Unit (FPCU) or by the ecu directly on injected models. Your lean condition is probably related to the either the carb or incomplete ignition due to the ignition coil not working properly with large amounts of AC current. I checked the power line from battery to alt, no resistance. Not the power output line - you need to check the sensing line going to the two pin plug on the back of the alt. It runs from the main junction to the back of the alt - through the fuse panel, idiot light and ignition switch. GD Edited May 28, 2009 by GeneralDisorder Link to comment Share on other sites More sharing options...
opus Posted May 28, 2009 Author Share Posted May 28, 2009 Your lean condition is probably related to the either the carb or incomplete ignition due to the ignition coil not working properly with large amounts of AC current. I am running it strictly on 12v from the battery. Alternator has not been in the equation for a week. Its not the carb and its not incomplete ignition. Its surely a fuel starvation issue. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted May 28, 2009 Share Posted May 28, 2009 Its surely a fuel starvation issue. You don't know that, but you can test your theory - gravity feed the carb with a funnel and some hose. GD Link to comment Share on other sites More sharing options...
ferox Posted May 28, 2009 Share Posted May 28, 2009 (edited) My wife's car is doing the exact same thing. Tonight she almost didn't make it home. Tested from the (+) battery post to the back of the alternator and got exactly 0.1mV [edit 0.1V]. Tested the coil switching action and it was extremely poor. Tested the coil itself and it was perfect. Fuses and fusible links are all good. The field sensor wire is not stock, so a PO has done something. This weekend her car will be getting a new GM alt. and charging circuit. Edited June 3, 2009 by ferox Link to comment Share on other sites More sharing options...
opus Posted May 29, 2009 Author Share Posted May 29, 2009 Vacuum leak was the culprit. Now, back to the alternator. :/ Link to comment Share on other sites More sharing options...
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